The present invention relates to a continuous-casting mold. More particularly this invention concerns such a mold which is water cooled.
In continuous casting, liquid metal, typically steel, is poured into one end of a throughgoing mold passage and is cooled so that, before it exits the opposite end of the passage, it has solidified and has enough structural integrity to form a strand that can be handled. Typically the passage is vertical with the molten metal being poured into the top and the solid strand being pulled out of the bottom.
In the system described in U.S. Pat. No. 6,192,972 of Mantovan the mold is made of male and female mold sections carried on respective endless chains having vertical adjacent stretches. As the mold sections move together at the top of the vertical stretches they form the passage, then move down slowly with the strand and separate at the bottom, to return on outer stretches. This system is extremely complex and difficult to control. The molten steel causes extreme wear and erosion of the mold sections which must be remachined and replaced often.
The mold of U.S. Pat. No. 4,390,057 of Reuter is formed of two parallel end plates and two parallel side plates together forming the mold passage. Ends of the side plates bears on end edges of the end plates, and shims are provided between the plates to maintain the passage in a predetermined shape. As the mold plates wear, shims are removed to maintain the shape. Such a system requires a complex harness arrangement to hold it together and no provision is made for cooling. The periodic adjustment for wear is difficult and requires a long down time.
The standard method of cooling such a mold is to provide large molded coolers that are bolted to the outside faces of the mold plates and through which water is passed so as to cool these outside faces and, by conduction, the metal in contact with the inside faces of the plates. To secure these coolers in place, it is necessary to provide the normally copper mold plates with threaded steel inserts cooperating with bolts, an arrangement that is, once again, quite complex.
German patent 25 49 011 of Rohrig provides cooling passages on outer faces of the mold plates that cooperate with other structure to form chambers a coolant can flow through. This system has the mold plates engaged together at angled end surfaces so that a rigid frame is needed to maintain the mold passage square. With time the wear and erosion of the plates causes leaks and breakouts that require wholesale replacement of the mold plates.
It is therefore an object of the present invention to provide an improved water-cooled continuous-casting mold.
Another object is the provision of such an improved water-cooled continuous-casting mold which overcomes the above-given disadvantages, that is which is of simple construction yet which is durable and which remains a tight seal even if worn.
A continuous-casting mold has according to the invention two parallel and spaced mold end plates having opposite ends and inner and outer faces and two parallel and spaced mold side plates extending generally perpendicular to the end plates, having inner and outer faces, and having opposite ends bearing on the respective side-plate ends. The inner faces form a generally rectangular mold passage having four corners. Respective rigid cooler plates bearing inward on the outer faces of the mold plates have ends at the corners. Respective clamps at the corners engage the cooler-plate ends, press the cooler plates inward on the mold plates, and thereby press the side-plate ends against the end-plate ends.
The cooler-plate ends in accordance with the invention are formed with angled bores and the clamp includes tie bolts each engaging at the respective corner through the respective bores of two adjacent cooler plates and each having ends bearing diagonally on the respective cooler-plate ends. The bolts are wholly out of contact with the mold plates and extend normally at 45xc2x0 to the planes of the mold plates.
Thus with this system the mold plates, which are subject to enormous abuse and wear in normal use, can be of relatively simple construction. They do not have to be finely machined, threaded, bored, and/or formed with cooling passages. Instead they can be basically flat castings and all that really needs to be done to them is machining a planar seal surface at each end.
Respective springs according to the invention are braced between each bolt and at least one of the respective cooler plates. These springs are packs of spring washers, one such pack of spring washers normally provided between each end of each bolt and the respective cooler plate. Thus the mold plates and cooler plates can even shift somewhat relative to each other without separating. This prevents breakout leaks and allows the system to accommodate to the often drastic temperature changes encountered in normal use.
The mold plates as mentioned above are all generally planar. The end mold plates have end edges extending perpendicular to the end plates and the side mold plates have end edges extending parallel to the side plates and bearing flatly on the end edges of the end plates. Thus the spacing between the side plates is determined by the width of the end plates, but the end plates can move limitedly parallel to the side plates to adjust the spacing between them. Only the mold-plate edges need be machined; the other surfaces can mainly be left as cast. Means are provided according to the invention for shifting the end plates parallel to the side plates. This means includes bolts engaging through the cooler plates and bearing on the side plates. As the end-plate coolers move in and out, the respective end plates move with them.
The mold plates have smooth and uninterrupted outer faces engaging the respective cooler plates. Each cooler plate forms a cavity open toward the outer face of the respective mold plate so that coolant can be pumped through the cavities to cool the plates. Furthermore, each cooler plate has an inner face flatly engaging the respective mold-plate outer face and formed with a normally annular groove open toward the respective mold plate. Respective seals seated in the grooves engage the respective mold-plate outer faces and prevent leakage from the cooling cavities.